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The present invention relates to a system and method for controlling the temperature of soft tissue through the use of a surgical device.
Researchers and physicians have long recognized the consequences of reduction of body temperature in mammals, including induction of stupor, tissue damage, and death. Application of freezing and near freezing temperatures to selected tissue is commonly employed to preserve tissue and cell (e.g. sperm banks); and application of extreme cold (far below freezing) is effective for tissue ablation. However, localized cooling (not freezing) of tissue has generally been limited to the placement of an xe2x80x9cice-packxe2x80x9d or a xe2x80x9ccold compressxe2x80x9d on injured or inflamed tissue to reduce swelling and the pain associated therewith. Localized cooling of internal organs, such as the brain, has remained in large part unexplored.
For example, xe2x80x9cbrain coolingxe2x80x9d has been induced by cooling the blood supply to the brain for certain therapies. However, as the effects of the cool blood cannot be easily localized, there is a systemic temperature reduction throughout the body that can lead to cardiac arrhythmia, immune suppression, intense shivering and coagulopathies.
Attempts have been made to localize cooling of the brain with wholly external devices, such as cooling helmets or neck collars. However, there are disadvantages associated with external cooling to affect internal tissue. For example, external methods do not provide adequate resolution for selective tissue cooling, and some of the same disadvantages that are associated with systemic cooling can occur when using external cooling devices.
During brain surgery, once a layer of tissue has been divided it must be held in place in order for the surgeon to proceed to the next level of dissection. Instruments that hold separated tissue apart can be hand-held or self-restraining retractors. In the specialized field of neurosurgery, surgeons must protect against the dangers of edema, or swelling of the brain, which may occur due to the pressure applied to the brain by the blade of a retractor. Although tissue retractors are designed to be strong enough to pull back tissue without obtrusively applying undue pressure to the operating area, edema may occur due to undue pressure applied by the retracting instrument to the brain tissue.
It has been known that post-neurosurgical edema can occur due to retraction trauma caused by a retractor in a neurosurgical procedure. For example, during an aneurysm or tumor surgery, retractors are often used to hold back lobes of brain tissue in order for the surgeon to gain access to a specific area. The pressure from the retractor is enough to traumatize the brain tissue and lead to post-surgical swelling, or edema.
It is therefore desirable to provide an improved device and method that allows for localized brain cooling while providing a layer of protection between the retractor and the brain tissue thereby preventing the possibility of trauma or edema caused by contact between the retractor blade and the brain tissue.
The present invention provides a device for decreasing the trauma imposed on soft tissue by extended contact with a retractor or retraction-like device during a surgical procedure thermally treating the tissue.
An exemplary prior art soft tissue retractor can include a deformable spatula connected to a handle element. To thermally treat the tissue, the soft tissue retractor can be configured to include a structure for enveloping and receiving at least a portion of the retractor spatula, where the structure is configured to control thermal energy transfer between the structure and the soft tissue.
For example, the structure can include a sheath dimensioned to envelope an end of the surgical instrument. A fluid conduit having a fluid inlet and a fluid outlet defining a fluid path through the fluid conduit can be attached to the exterior surface of the sheath, where the fluid conduit creates a thermal transfer region. The sheath is positioned on the spatula such that the thermal transfer region is in thermal relation with the retracted soft tissue.
To provide thermal control, the thermal transfer region is in fluid communication with a thermally-conductive fluid source such that a fluid circulation circuit is defined through the thermal transfer region.
Once the soft tissue is retracted, the thermal transfer region being in thermal communication with the soft tissue, the thermally-conductive fluid enters the thermal transfer region thermally affecting the soft-tissue. Simultaneously, thermal-conductive fluid is evacuated from the thermal transfer region. In this manner, the thermal transfer region affects a specific controlled temperature to the soft tissue.
All patents, patent applications and publications referred to or cited herein, or from which a claim for benefit of priority has been made, are incorporated by reference in their entirety to the extent they are not inconsistent with the explicit teachings of this specification, including: U.S. Pat. No. 3,882,855 to Schulte et al., U.S. Pat. No. 5,709,646 to Lange, and U.S. Pat. No. 5,007,409 to Pope.